1. Field of the Invention
The invention relates to a process and to an apparatus for the bubble-free gassing of liquids, especially of culture media especially for propagating tissue cultures.
2. Brief Description of the Prior Art
The purpose of gassing liquids is to introduce and to desorb gases. Especially when multiplying animal cells in culture media, adequate supply of oxygen and adequate removal of carbon dioxide presents a problem if cell numbers of more than 10.sup.6 cells per ml of culture medium are to be achieved. Since with so-called surface gassing only a small volume of liquid can be gassed, there has been a change to so-called submersed gassing. Although the required gasification rates with air or pure oxygen can be achieved in this process, undesirable foam formation occurs at the surface of the medium. Frequently cells and also microcarriers float in this foam, and this results in a reduction in the efficiency of the culture.
To solve this problem a method has become known in which gas exchange occurs across an immersed membrane sheet. In this process, the gassing is carried out with closed or open-pored membranes that are arranged in the liquid which is agitated by a stirrer. It is to be seen as a disadvantage in this process that the movement of the liquid is in many cases possible only under certain conditions and at a very low number of revolutions since the tissue cultures are extremely sensitive to shearing forces.
The problem underlying the invention is to provide a process and an apparatus, of the type mentioned at the beginning, for the bubble-free gassing of liquids, especially of culture media for propagating tissue cultures, which process and apparatus allows as uniform as possible a distribution of gas introduction and gas desorption in a simple and effective manner without mechanical damage to the constituents of the liquid medium, like cells.